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Cambria FTC: ARIB STD B37 Captions Extraction in MXF and Conversion to WebVTT and Burning the Captions in Video

Version 1 - 11/28/2023

Table of Contents​

Note:​

This workflow supports ARIB STD B37 caption extraction from MXF files only as of 11/28/2023. Captions in TS streams may be supported in the future.

Step 1: Detecting ARIB STD B37 Captions​

Submit a job through API:

POST: https://localhost:8648/CambriaFC/v1/Jobs

Sample JobXML for the Body of the API call:​

-Please replace SourceFilename with the path to your source

-Please replace OutputFilename with the output location and name you desire

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The job will be queued to the FTC Manager and complete.

Sample output:​

Please search for Metadata HasSTDB37 in the output. If it’s set to 1 then the source has captions otherwise no captions have been detected on the source.

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Step 2: Extract Captions to WebVTT​

FTC will extract captions from a source file and generate a WebVTT output.

  1. Import your source into FTC.

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  1. Add a closed caption exporter preset.

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  1. In the preset editor:
    • Set Container to Closed Captions.
    • Source Caption Mode should be ARIB-STD-B37.
    • Specify an output directory and filename.
    • Enable Include Font Size info (cue) to preserve font size.

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  1. Queue the job.

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  1. The job will process in Cambria Manager, where you can monitor status.

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Sample WebVTT Output:

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Step 3: Burn in WebVTT Captions on Video​

  1. Import the source as in previous steps and add a source-side filter.

  2. Apply Timecode Overwrite Filter to reset timecode to match the WebVTT file.

  3. Add Subtitle Burn-In as a filter.

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Next Please choose Subtitile burn in as the filter

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  1. Configure the filter:
    • Set Subtitle Source Type to Web Video Text Tracks Format.
    • Browse and select the WebVTT file generated in Step 2.
    • Enable:
      • Use Embedded Formatting
      • Captions are Formatted with ARIB STD-B37
      • Use Background
    • Use a monospaced font (e.g., Noto Sans JP from Google Fonts).

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  1. Ensure two source-side filters are set in this order:

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  1. Switch to the Encoding Tab, add an encoding preset.

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  1. Queue the job in Manager and wait for the output video with burnt-in subtitles.

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